2:00 PM

Do Extended High Frequency Audiometry Results Influence Treatment Recommendations and Hearing Aid Uptake in Cases of Borderline Candidacy: A Multiple Case Study Review.

Andreas Seelisch, Sally Norris, and Adrienne Harrison (Hearing Solutions, Western University), Abstract #119.

Speaker
Andreas Seelisch, MSc, Director, Audiology, Hearing Solutions

Objectives
This pilot study explores whether adding extended high frequency (EHF) audiometry to a standard diagnostic test battery influences treatment recommendations or hearing aid uptake.

Background
There is a significant body of literature that indicates standard audiometric findings alone are a poor predictor of hearing aid candidacy and hearing aid uptake. Studies have illustrated there is especially poor consensus on how mild losses are managed, with no clear audiometric criteria for hearing aid candidacy, there is significant variability in how clinicians resolve these cases. It is hypothesized that EHF audiometry may be sensitive to hearing difficulties for a subset of individuals with otherwise clinically insignificant findings. Access to these results may better inform clinicians on how to manage cases and support hearing aid uptake where results confirm patient experiences.

Methods
Case studies were selected from a clinic piloting routine use of EHF audiometry in their diagnostic test battery. Normal pure tone averages in conjunction with self-reported hearing difficulties were used as inclusion criteria.

Results
A large volume of cases were identified in which clinical findings in the standard audiometric range would likely have been viewed as clinically insignificant. Several unique cases emerged where the addition of EHF testing may have contributed to hearing aid recommendations and/or hearing aid uptake. Cases with noteworthy similarities or differences were compared for contrast.

Conclusions
EHF audiometry findings appear to have some impact on hearing aid recommendations and uptake for a subset of patients with normal pure tone averages. These findings will inform a larger project in which aggregate data can better determine the effect EHF testing has as a criterion for hearing aid recommendations and/or on hearing aid uptake for patients in this population.

 

2:13 PM

Psychophysical Tuning Curves in a Family with Genetic Hearing Loss Due to Kcnq4 Gene.

Sushma Singh, Shailendra Singh, Anne Griffin, Terry-Lynn Young, and Susan Stanton (Western University, Lakehead University, and Memorial University), Abstract #136.

Speaker
Sushma, Singh, PhD Candidate, Western University

Objectives
The objective of this study is to evaluate cochlear and auditory nerve function in human subjects with SNHL due to a KCNQ4 gene mutation.

Background
The fact that mutations in the potassium channel gene, KCNQ4, causes autosomal dominant sensorineural hearing loss (SNHL) is well known. However, the site of lesion along the auditory pathway is uncertain. Early studies in mice indicated that kcnq4 gene expression was restricted to the outer hair cells. However, more recent studies show this gene is expressed at multiple sites in the auditory pathway from the cochlea to the brainstem.

Methods
Comprehensive phenotyping tests were conducted in a 7 generational family from Newfoundland, with SNHL caused by the same KCNQ4 mutation. Psychophysical tuning curves (SWPTCs) were measured in 12 affected family members and analyzed by measuring percent shift in the tuning curve tip frequency; a technique developed to identify cochlear dead regions. In addition, we used Distortion Product Otoacoustic Emissions (DPOAE) to evaluate outer hair cell function.

Results
Of the 76 SWPTC measurements in 12 family members, psychophysical tuning curves resulted in 4 out of 12 individuals showing greater than a 10% tip shift for probe frequencies in the low to mid-frequency range. DPOAE sweeps identified responses in frequency regions with better hearing sensitivity, with absent responses in regions with worse hearing thresholds, usually in the mid to high-frequency range.

Conclusions
DPOAE results confirm outer hair cell dysfunction in all affected family members, supporting the mouse model that showed disruption at the level of outer hair cells, while SWPTCs indicate frequency-specific cochlear dead regions in 4 individuals. Together, these results provide evidence of inner hair cells and/or auditory nerve involvement in addition to outer hair cells dysfunction as the sites of lesion for this family.

 

2:27 PM

Electrophysiological Measures of Spatial Hearing in Children Who Use Bilateral Cochlear Implants.

Angela Fung, Jaina Negandhi, Alan Blakeman, Robel Alemu, Sharon Cushing, Blake Papsin, and Karen Gordon (University of Toronto and The Hospital for Sick Children), Abstract #137.

Speaker
Angela Fung, BSc, University of Toronto; Hospital for Sick Children

Objectives
We aim to assess the electrophysiological acoustic change complex (ACC) response as a measure of spatial hearing in children using bilateral cochlear implants (CIs).

Background
Bilateral CIs provide hearing advantages to children, but spatial hearing remains impaired perhaps due to abnormal access to binaural cues such as inter-aural level differences (ILDs) during important developmental periods. We hypothesized that the acoustic change complex (ACC), an evoked potential measure of cortical sensitivity to sound changes, can: 1) be measured in pediatric bilateral CI users to ILD changes, and 2) quantify reduced sensitivity to ILDs in children with bilateral CIs.

Methods
Electroencephalography (EEG) was recorded at a central-midline electrode (CZ), referenced to midline electrodes placed at the back of the head, in response to a 1 kHz pure tone with 100% amplitude- modulation at 40Hz. This stimulus was first presented bilaterally at ILD=0 for 1 s and then with an ILD (6 conditions: ±4-, 10-, and 20- dB SPL, where + is weighted to right and – is weighted to left) for another 1 s. The stimuli were presented through research processors in 15 participants using bilateral CIs and through insert earphones in 6 typically-developing peers.

Results
Participants in the CI group were first implanted at mean(SD)=5.8(4.7) years, and tested at (mean(SD)=14.2(3.1) years; 11 were simultaneously implanted and 4 were sequentially implanted, with an inter-implant delay of mean(SD)=2.1(2.1) years. The children in the control group were (mean(SD)=14.6(2.7) years old at testing. Clear cortical responses were obtained in both groups to the onset, the change (ACC), and offset of sound. Preliminary analyses also suggest that the ACC amplitude increases with increasing ILD changes in both groups.

Conclusions
The ACC can quantify cortical detection of ILD cues with potential utility for improving spatial hearing in children with bilateral CIs.

 

2:42 PM

Impacts of Hearing Device Prescriptive Formulas on Word Recall – A Pilot Study with Normal-Hearing Participants.

Alex Gascon and William Hodgetts (University of Alberta), Abstract #123.

Speaker
Alex Gascon, R.Aud, Registered Audiologist, PhD student, Institute for Reconstructive Sciences in Medicine, Edmonton

Objectives
Using a Sentence final Word Identification and Recall (SWIR) experiment, this pilot study explored the impact of hearing device prescriptive formulas on word-recall scores in normal-hearing participants.

Background
Previous studies show that the National Acoustic Laboratories (NAL) and Desired Sensation Level (DSL) prescriptive formulas offer similar audibility and word identification scores for adult hearing aid users. However, comparisons have not been made using tests within the framework of listening effort such as the SWIR. SWIR experiments may detect effects of prescriptive formulas on listening effort that are not captured by traditional speech perception tests.

Methods
The two prescriptive formulas were compared using a SWIR experiment in a repeated measure design. A group of 12 normal- hearing participants heard sentences over competing multi-talker babble in three conditions: (1) unprocessed, (2) processed with DSL-BCD v1.1 and (3) processed with a version of NAL used in bone- conduction hearing devices. The impact of the serial position of the sentences (primacy, asymptote and recency) and the word identification scores were also analysed.

Results
A Friedman’s test comparing mean word-recall scores across conditions showed no statistically significant differences (χ2(2) = 0.93, p = 0.63, Unprocessed: 80.21%, DSL: 80.17%, NAL: 80.28%).The word recall scores were worse for sentences in the asymptote compared to the primacy and recency positions, across all conditions. The word identification scores were not statistically different between conditions (χ2(2) = 5.30, p = 0.07).

Conclusions
Using word-recall scores as a surrogate for listening effort, this study suggests that speech altered by these two prescriptive formulas does not require greater listening effort than unprocessed speech in normal-hearing individuals. Future SWIR studies with hearing-impaired individuals are needed to better understand the potential impact of prescriptive formulas on word- recall and listening effort.